Method and instruments for interbody fusion and posterior fixation through a single incision

ABSTRACT

Methods and devices for providing access to an intervertebral disc using the patient&#39;s bony pedicle as an anchoring spot for a pedicle screw that temporarily attaches to an access port are disclosed herein. The disclosed methods and devices can eliminate the need for a surgical table as an anchor, as well as the need for components extending from the table to the port at the access site, thereby unencumbering the surgeon&#39;s view and workspace while providing minimally invasive access.

CONTINUING DATA

This application is a continuation of U.S. application Ser. No.15/421,195, filed Jan. 31, 2017. U.S. application Ser. No. 15/421,195claims priority from U.S. Application No. 62/292,205, filed Feb. 5,2016. The entire contents of each of these applications are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

Articulating and expandable interbody fusion devices (IBDs) make itpossible to perform interbody fusion procedures through a relativelysmall unilateral skin-and-facia incision compared to non-articulating ornon-expandable IBDs. However, interbody fusion procedures are oftensupplemented with bilateral posterior fixation via pedicle screw-and-rodconstructs whose large sizes require alteration of the IBD surgicalaccess plan to accommodate posterior construct placement. The large sizeof the pedicle screw construct, when paired with interbody fusion,typically requires either lengthening of the incision used for IBDplacement (mini-open) or additional incisions (percutaneous) throughwhich the pedicle screws and rods are placed. These alterations mayinhibit articulating and expandable IBD technology from realizing theirfull potentials as minimally invasive interbody fusion solutions.Therefore, a need exists for a means of achieving interbody fusion andposterior fixation through a single incision.

In addition, when minimally invasive spinal surgery procedures are used,the procedures typically include inserting a port through the initialincision and then passing the relevant tools and implants through theport on their way to the spine. Typically, the port is anchored tosurgical table with large and bulky assembly components, thereby causingobstruction of the surgeon's view and workspace. Table mounts also haveto be adjusted by a non-sterile member of the operating team, whichtakes control from the surgeon.

US 2011-0130634 (Solitario) discloses a patient-mounted retractionsystem.

SUMMARY OF THE INVENTION

A method of providing access to an intervertebral disc has beendeveloped that involves using the patient's bony pedicle as an anchoringspot for an anchor (such as a pedicle screw) that temporarily attachesto the access port via an anchor extension (such as a screw extension).Because this new procedure eliminates the need for the surgical table asan anchor, it also eliminates the assembly components extending from thetable to the port at the access site, thereby freeing the surgeon's viewand workspace from bulky instruments while providing minimally invasiveaccess. Preferably, the anchor extension is pivotally attached to theproximal end of the port so that it can pivot towards the center of theport and thereby provides access to two vertically-adjacent pedicles andto the intervertebral space therebetween.

Therefore, in accordance with the present invention, there is providedan assembly comprising:

a) an anchor extension comprising a shaft having a distal end portioncomprising a receiver adapted for receiving an anchor and a proximal endportion comprising a pivoting feature,

b) a port comprising:

-   -   i) a tubular wall defining a central passageway,    -   ii) a longitudinal slot in the wall defining opposed ends of the        wall,    -   iii) opposed flanges extending radially from each end of the        wall, and    -   iv) a mating feature disposed in each opposed flanges adapted to        pivotally mate with the pivoting feature of the screw extension.

wherein the mating feature of the tube pivotally mates with the pivotingfeature of the anchor extension.

Also in accordance with the present invention, there is provided amethod of mounting a port to a patient having spinal surgery,comprising:

-   -   a) passing a dilator through an incision in the skin of the        patient towards a pedicle,    -   b) passing a port having a passageway over the dilator, wherein        the port comprises a tubular wall defining a central passageway,    -   c) removing the dilator,    -   d) passing an anchor assembly comprising a distal anchor and a        proximal extension at least partially through the incision,    -   e) inserting the distal anchor into the pedicle,    -   f) pivotally attaching the proximal extension to the port.

Also in accordance with the present invention, there is provided aspinal assembly comprising:

-   -   a) an anchor extension comprising a shaft having a distal end        portion comprising a receiver adapted for receiving an anchor        and a proximal end portion comprising a pivoting feature,    -   b) an anchor received in the receiver of the screw extension,    -   c) a port comprising:        -   i) a tube defining a first longitudinal passageway,        -   ii) a flange extending radially from the tube and having a            throughole longitudinally disposed therein,    -   iii) a bushing having an inner perimeter and an outer perimeter,        wherein the outer perimeter radially contacts the throughhole,        and

wherein the anchor extension passes through the inner perimeter of thebushing.

Also in accordance with the present invention, there is provided aninstrument assembly for performing MIS surgery on a spine, comprising:

-   -   a) a port having a proximal end portion, a distal end portion,        and an axial passageway defining a centerline, and    -   b) an anchor extension having a distal end portion,    -   wherein the anchor extension is pivotally attached to the        proximal end portion of the port.

DESCRIPTION OF THE FIGURES

FIG. 1 discloses a first step of an embodiment wherein a paramedian skinand fascia incisions is made over the site through which interbodyaccess is planned.

FIG. 2 discloses a second step wherein a conventional dilator is used todilate and wand over the facet through which interbody access isplanned.

FIG. 3 discloses a third step in which an integrated tubular dilatorport is placed over the standard dilator, and the inner dilator isremoved.

FIG. 4 discloses a step in which pedicle preparation is performedthrough the integrated dilator port for at least one pedicle screw.

FIGS. 5A-B discloses a step in which a pedicle screw attached to a screwextension is inserted into one pedicle through the integrated dilatorport, resulting in anchoring of the screw extension.

FIG. 6A discloses a step in which the integrated dilator port isproximally engaged with the screw extension via a spherical male featureon the extension and a proximally-located slotted cylindrical femalefeature on the dilator port. The dilator port height and angle areadjusted via the sphere-in-cylinder configuration, and the assembly istightened via one of a variety of clamping mechanisms (such as athreaded clamping mechanism).

FIGS. 6B-D disclose different embodiments and views of the assembly.

FIGS. 6E and 6F disclose alternate views of a port.

FIG. 6G-I disclose side and cross-sectional views of a screw extensionhaving a bulb.

FIGS. 6J-K disclose the assembly further comprising a locking featureadapted to lock the screw extension between the flanges of the port.

FIG. 7 discloses a step in which facetectomy and discectomy areperformed and the IBD is placed through the integrated dilator port.

FIG. 8 discloses a step in which the angle and height of the dilatorport are adjusted, for subsequent screw placement. Access to theadjacent screw trajectory is afforded by the slot in the dilator portthat allows it to pass over the screw extension.

FIG. 9 discloses a step in which an adjacent level screw is placedthrough the dilator port,

FIG. 10 discloses a step in which the dilator port is disengaged fromthe screw extension and the screw extension is removed from the screw.

FIG. 11 discloses a step in which heads are assembled to the screwshanks through the dilator port.

FIG. 12 discloses a step in which a rod is inserted through the dilatorport, which is afforded by the slot in the dilator port.

FIG. 13 discloses a step in which set screws are placed through thedilator port and the screw/rod construct is tightened.

FIG. 14 discloses a step in which the dilator port is removed from theincision for subsequent closure.

FIG. 15 discloses an alternate embodiment of the assembly in which theport has a fully enclosed passageway and the screw extension is receivedin a bushing disposed in a flange extending from the port tube.

FIGS. 16-17 are alternate views of the assembly of FIG. 15 implanted ina patient's spine.

FIGS. 18A-B disclose the screw extension of the invention attached to apedicle screw in a monoaxial or co-axial fashion.

FIGS. 19A-B disclose the screw extension of the invention attached to apedicle screw in a polyaxial (lockable) fashion.

DETAILED DESCRIPTION OF THE INVENTION

Now referring to FIG. 1, a paramedian skin and fascia incision 100 ismade over the site through which interbody access is planned. Nowreferring to FIG. 2, a conventional dilator 99 is used to dilate andwand over the facet through which interbody access is planned. Nowreferring to FIG. 3, an integrated tubular dilator port 21 is placedover the standard dilator, and the inner dilator is removed.

FIG. 4 discloses a step in which pedicle preparation is performedthrough the integrated dilator port 21 for at least one pedicle screw.Thus, in some embodiments, the assembly further comprises apedicle-preparation tool 101 at least partially disposed in thepassageway. In some embodiments thereof, the tubular wall has a distalend, the pedicle-preparation tool has a working end, and the working endof the tool extends past the distal end of the tubular wall.

Now referring to FIGS. 5A and 5B, a pedicle screw 35 is attached to ascrew extension 3 is inserted into one pedicle through the integrateddilator port.

FIG. 6A discloses a step in which the integrated dilator port isproximally engaged with the screw extension via a spherical male featureon the extension and a proximally-located slotted cylindrical femalefeature on the dilator port. The dilator port height and angle areadjusted via the sphere-in-cylinder configuration, and the assembly istightened via a threaded clamping mechanism.

FIGS. 6B-D disclose an assembly 1 comprising:

-   -   a) a screw extension 3 comprising a shaft 5 having i) a distal        portion 7 comprising a threaded receiver 9 located at the distal        end portion 10 and adapted for receiving a screw and ii) a        proximal portion 11 comprising a pivoting feature 13 and a head        14 located at the proximal end 15 of the screw extension,    -   b) a port 21 comprising:        -   i) a tubular wall 23 defining a central passageway 25,        -   ii) a longitudinal slot 27 in the wall defining opposed ends            29 of the wall,        -   iii) opposed flanges 31 extending radially from each end of            the wall, and        -   iv) a mating feature 33 disposed in each opposed flanges            adapted to pivotally mate with the pivoting feature of the            screw extension.

wherein the mating feature of the tube pivotally mates in a joint withthe pivoting feature of the screw extension.

FIG. 6B also comprises a locking feature 36 that locks the axialposition of the screw extension vis-à-vis the port.

In some embodiments, the pivoting feature comprises a substantiallyspherically-shaped portion or bulb 13 extending from the shaft, as shownin FIGS. 6B-D. The spherical nature of this pivoting feature allowspolyaxial pivoting (or “wanding”) about the joint. The ability to wandthe screw extension (i.e., pivot the screw extension about the joint)allows the surgeon to reach a vertically-adjacent pedicle with the samescrew extension, thereby allowing two screws to be placed through asingle port location.

Also as seen in FIG. 6B, the port has a circumferential ridge 37, whichallows for controlling the rigidity required for clamping. The ridgehelps transmit the clamping load.

FIG. 6C discloses an assembly substantially similar to that of FIG. 6B,except that the port does not have a circumferential ridge, and thelocking feature have been omitted for clarity.

FIG. 6D shows a cross-section of an assembly substantially similar tothat of FIGS. 6B and C. The FIG. 6D cross-section shows the bulb 13 ofthe screw extension as pivotally contacting the hemicylindrically-shapedlongitudinal depressions 33 of the port.

FIGS. 6E and 6F show alternate embodiments of the port component 21disattached from the screw extension.

In FIGS. 6E and 6F, the mating features of the port flanges that allowmating with the screw extension are hemicylindrically-shapedlongitudinal depressions 33 disposed in each of the opposed flangesadapted to pivotally mate with the pivoting feature of the screwextension. The hemicylindrical nature of the depressions allow the bulb13 of the screw extension to slide in a proximal-distal (axial)direction, thereby facilitating initial attachment of the bulb to theport and allowing the surgeon freedom to choose the height of the jointin the assembly so as to reduce tissue creep distal to the port. Also inFIGS. 6E and 6F, the flanges have opposed holes 41 adapted to receivethe pin of a locking feature (not shown).

In some embodiments, each mating feature comprises a depression.Preferably, the depression has a curve that allows the screw extensionto pivot therein. In some embodiments, each mating feature comprises asubstantially hemicylindrically-shaped depression extending in theproximal-distal direction that allows the screw extension to polyaxiallypivot therein, thereby allowing wanding.

In some embodiments, each mating feature 33 comprises a substantiallycylindrically-shaped depression having a longitudinal axis extending ina direction substantially parallel to the central passageway, as shownin FIGS. 6E and 6F. The shape of this depression not only allows theabove-mentioned pivoting, it also allows axial movement of the pivotingfeature of the screw extension in a direction parallel to thelongitudinal axis of the passageway. This freedom of axial movement inthe screw extension is important because it allows the surgeon to matethe distal end of the port with the bony anatomy to minimize soft tissuecreep without having to adjust the screw depth.

FIGS. 6G-6I disclose different views of a screw extension. In FIG. 6G,the shaft of the screw extension has a substantially spherically-shapedbulb extending therefrom. This bulb, which is located on the proximalportion of the screw extension, is the pivoting feature of the screwextension that pivots with the depressions of the flanges of the port.FIG. 6F also discloses a threaded receiver on the distal end portion ofthe extension that is adapted for attaching to a pedicle screw. FIG. 6His a cross-section of FIG. 6G, which reveals a bore 45 adapted forpassage of a pedicle screw. Proximal to the bulb of FIGS. 6G and 6H is ahead located at the proximal end of the screw extension and adapted toattach to a screw driver. The head has a pair of diametrically alignedholes 47 adapted to retain the extension on the screw driver duringinsertion. FIG. 6I shows a screw extension having a spherical bulbpivoting feature 13, and distal threads 9.

In some embodiments, as in FIG. 6I, the assembly further comprises ascrew 35 received in the receiver of the screw extension.

Now referring to FIGS. 6J-K, in preferred embodiments, the assemblyfurther comprises a locking feature 36 adapted to lock the screwextension between the flanges of the port. This locking mechanism keepsthe screw extension attached to the port with its axial positionmaintained while allowing the screw extension to pivot about the joint.In some embodiments, the locking feature is produced by providingopposed holes in the opposed flanges, inserting a threaded pin 39through the opposed holes, and tightening a nut 41 over a distal end ofthe threaded pin. The resulting locking feature of is shown in FIG. 6B.

FIG. 6K further shows, in addition to the locking feature, the slot 27defined in the port by the two ends 29 of its wall.

Now referring to FIG. 7, facetectomy and discectomy are performed andthe IBD is placed through the integrated dilator port 21.

Now referring to FIG. 8, the angle and height of the dilator port areadjusted, for subsequent screw placement. Access to the adjacent screwtrajectory is afforded by the slot in the dilator port that allows it topass over the screw extension.

Now referring to FIG. 9, an adjacent level screw is placed through thedilator port,

Now referring to FIG. 10, the dilator port is disengaged from the screwextension and the screw extension is removed from the screw.

Now referring to FIG. 11, heads are assembled to the screw shanksthrough the dilator port.

Now referring to FIG. 12, a rod is inserted through the dilator port,which is afforded by the slot in the dilator port.

Now referring to FIG. 13, set screws are placed through the dilator portand the screw/rod construct is tightened.

Now referring to FIG. 14, the dilator port is removed from the incisionfor subsequent closure. Although FIG. 14 shows final tightening as well,final tightening can occur before or after the port is removed.

Referring now to FIG. 15-17, there is provided an assembly comprising:

-   -   a) a screw extension comprising a shaft having a distal end        portion comprising a receiver adapted for receiving a screw and        a proximal end portion comprising a pivoting feature,    -   b) a screw received in the receiver of the screw extension.    -   c) a port 51 comprising:        -   j) a tube 53 defining a first longitudinal passageway 55,        -   ii) a flange 57 extending radially from the tube and having            a throughole 59 longitudinally disposed therein,        -   iii) a bushing 61 having an inner perimeter 63 and an outer            perimeter 65, wherein the outer perimeter radially contacts            the throughhole, and

wherein the screw extension passes through the inner perimeter of thebushing.

In alternate embodiments related to FIGS. 15-17, a vertical slot isprovided in the port so as to fulfill the need of being able to performthe complete procedure through a single incision.

Preferably, the bushing is a split bushing intended to transmit aclamping load from the port housing to the screw extension to maintainboth rotational and axial stability of the port relative to the screwextension. Preferably, the bushing is flexible to allow wanding of thescrew extension. Also preferably, the bushing is located adjacent aproximal end of the tube, again to allow wanding of the screw extension.The ability to wand the screw extension (i.e., pivot the screw extensionabout the bushing) allows the surgeon to reach an adjacent pedicle withthe screw extension, thereby enabling two screws to be placed through asingle port location.

The instruments associated with the proposed solution would likely beclassified as general surgical instruments. The screw extension wouldinterface with a pedicle screw system, such as the MATRIX or EXPEDIUMsystems marketed by DePuy Synthes Spine (Raynham, Mass.). Similar to theMATRIX system distraction tips, the screw extension could interface witha headless screw shank 75 in a monoaxial fashion (as shown in FIGS.18A-B) or with a polyaxial screw head 77 in a lockable polyaxial fashion(as shown in FIGS. 19A-B).

The invention claimed is:
 1. An assembly comprising: an access porthaving a proximal end portion and a distal end portion and defining alongitudinal passageway extending through the port, the access portfurther defining a longitudinal slot in the access port; an anchorextension comprising a shaft having a proximal end portion pivotallycoupled to the proximal end portion of the access port and a distal endportion comprising a receiver adapted for receiving an anchor, whereinthe anchor extension is configured to pivot through the slot of theaccess port.
 2. The assembly of claim 1 wherein the anchor extension ispivotally coupled to the proximal end portion of the access port outsidethe longitudinal passageway.
 3. The assembly of claim 1 wherein theproximal end portion of the anchor extension comprises a pivotingfeature.
 4. The assembly of claim 3 wherein the pivoting featurecomprises a substantially spherically-shaped body extending from theshaft.
 5. The assembly of claim 3 wherein the proximal end portion ofthe access port comprises opposed flanges disposed about the slot andextending radially away from the access port, each of the opposedflanges defining a mating feature configured to pivotally mate with thepivoting feature of the anchor extension.
 6. The assembly of claim 5wherein the mating feature defined in each of the opposed flangescomprises a substantially spherical-shaped depression.
 7. The assemblyof claim 5 wherein the mating feature defined in each of the opposedflanges comprises a substantially cylindrical-shaped depression having alongitudinal axis extending in a direction substantially parallel to thelongitudinal passageway of the access port.
 8. The assembly of claim 5wherein the mating feature defined in each of the opposed flangescomprises a hole.
 9. The assembly of claim 5 further comprising alocking feature adapted to lock the anchor extension between theopposing flanges of the access port.
 10. The assembly of claim 9 whereinthe opposed flanges of the access port have opposed holes and thelocking feature comprises a threaded pin inserted through the opposedholes in the flanges to lock the anchor extension in place.
 11. Theassembly of claim 1 wherein the anchor is a screw.
 12. A surgicalmethod, comprising: passing an access port at least partially through anincision made in a patient, the access port having a proximal endportion and a distal end portion and defining a longitudinal passagewayextending through the port, the access port further defining alongitudinal slot in the access port; inserting an anchor extension atleast partially through the longitudinal passageway of the access port;and pivotally coupling a proximal end portion of the anchor extension tothe proximal end portion of the access port.
 13. The surgical method ofclaim 12, further comprising: disposing a first anchor coupled to adistal end portion of the anchor extension onto a first pedicle of apatient's spine.
 14. The surgical method of claim 13, furthercomprising: attaching a second anchor to the distal end portion of theanchor extension; pivoting the anchor extension through the slot of theaccess port towards a second pedicle of the patient's spine; anddisposing the second anchor onto the second pedicle.
 15. The surgicalmethod of claim 14, further comprising: inserting a rod through thelongitudinal passageway and the slot of the access port; and attachingthe rod to the first anchor and the second anchor.
 16. The surgicalmethod of claim 12, further comprising: anchoring the anchor extensionto a pedicle of a patient's spine; and positioning the access port bypivoting the access port about the anchor extension.
 17. The surgicalmethod of claim 16, wherein the access port is configured to pass overthe anchor extension through the slot of the access port when pivotingthe access port about the anchor extension.